Comments

[1]
Chess players interested in ches480 or chess960 (a.k.a. Fischer Random
Chess, FRC) may be interested to hear that a major new chess960 book has
been published (Jan 2006). Title is:
'Play Stronger Chess by Examining Chess960:
Usable Strategies of Fischer Random Chess Discovered'
(ISBN 0-9774521-0-7)
Searching in Amazon.com or Google.com will find the book.
Or visit http://CastleLong.com/
[2]
I suspect that chess480, with its castling rule having the King move two
squares instead of to the traditional squares c1 or g1, would lead to
LESS
OPPOSITE WING castling games than would chess960/FRC.
Thus I suspect the draw rate would be higher in chess480 than in
chess960.
Generally a higher draw rate is bad.
In my chess960 book I describe a tweak of the chess960 castling rule,
designed to increase the rate of opposite wing castling. Statistics show
that the draw rate is lower when the two players castle to opposite
wings.
Opposite wing castling is almost rare in traditional 'chess1', which
may
be considered a flaw in the engineering of the rules (choices made when
chess1 was invented in the 1400's). Basically, my rule would give the
second player to castle more freedom to choose the destination square of
his castling king, if but only if he castles to the opposite wing.
Thank you.
Gene Milener

I am just about to implement Chess480 in my SMIRF program. SMIRF will then randomly select positions from Chess960, but only those, where the white king is right sided to the queen. Thus the redundant half of mirrored starting arrays is filtered out. To distinguish its FEN, a preceding 'm' is placed immediately before the castling tags block, as specified in current X-FEN.

Rather than thinking of 2 sets of 480 positions, perhaps it's better to think of 480 sets of 2 positions. The two positions in each set are related by left-right reflection, and have equivalent strategy trees.

I agree with John that it's aesthetically preferable to play all 960 positions, but if you want to choose just one from each pair, how about the one where the Queen is to the left of the King in White's starting position?